1. Field of the Invention
The present invention relates to a dye-containing negative curable composition, a color filter using the dye-containing negative curable composition, and a method of producing the color filter. More specifically, the present invention relates to a dye-containing negative curable composition which structures a color filter used in liquid crystal displays (LCD) and solid-state image sensors (CCD, CMOS and the like) and is preferable in the formation of printed images.
2. Description of Related Art
Known methods of producing a color filter used in liquid crystal displays and solid-state image sensors include a dye method, a print method, an electrodeposition method, and a pigment-dispersion method.
Among these, the pigment-dispersion method is a method of producing a color filter by a photolithographic method using a colored radiosensitive composition including a pigment dispersed in a radiosensitive composition of various kinds. This method has the advantage of stability in light, heat or the like, due to the use of a pigment. Further, since patterning is conducted by the photolithographic method, this method is considered to be suitable for producing a color filter for a large-sized color display having high positional accuracy and high resolution.
In the pigment-dispersion method of producing a color filter, a color filter is obtained by repeating a process for each color, the process including forming a coating film by applying and drying a radiosensitive composition onto a glass substrate by a spin-coater or a roll-coater, forming a colored pixel by exposing the coating film to light in a pattern-wise manner, and developing the exposed coating film.
For example, Japanese Patent Application Laid-Open (JP-A) No. 2-181704 discloses a pigment-dispersion method using a negative photosensitive composition including an alkali-soluble resin, a photopolymerizable monomer and a photopolymerization initiator.
On the other hand, in recent years, even higher resolution in color filters used in solid-state image sensors has been desired. However, it is difficult to achieve further improvements in resolution in a conventional pigment-dispersion system, since there are problems such as occurrence of color irregularities caused by coarse particles in the pigment. Therefore, the pigment-dispersion system is not suitable for applications in which a fine-sized pattern is required, such as solid-state image sensors.
In view of the above-mentioned problems, a technique of using a dye instead of a pigment has been proposed (for example, see JP-A No. 6-75375).
There has been a demand for color filters used in solid-state image sensors in recent years to have a film thickness of 1 μm or less. In order to achieve such a small thickness, the concentration of a dye needs to be increased. Since some dyes exhibit low solubility in an organic solvent due to their structure, there have been cases in which difficulty in preparing a resist solution is caused by insufficient solubility of the dye when conventional solvents (such as ethyl lactate or propylene glycol monomethyl ether acetate) are used.
Further, a technique of using cyclohexanone, which has a relatively high ability of dissolving a dye compared with other organic solvents, is known. However, when cyclohexanone is used, coating uniformity may deteriorate in some cases.
The present invention has been made in view of the above circumstances, and provides a dye-containing negative curable composition that exhibits excellent coating uniformity, a color filter with colored pixels having a uniform film thickness, and a method of producing the color filter.